Comparative clinical study of the efficacy and safety of a S-metoprolol ER tablet versus a racemate metoprolol ER tablet in patients with chronic stable angina

Abstract

To compare the efficacy and safety of a S-metoprolol extended release (ER) tablet (50 mg) versus a racemate metoprolol ER tablet (100 mg) in the management of angina. An open-label, prospective, comparative study in a clinical setting was conducted in Indian patients. Patients (n = 50 in each group) with a history of angina pectoris, with or without hypertension, were administered study medications in a sequential 1:1 manner once daily for 8 weeks. The primary efficacy variable was a mean change from baseline in the number of angina attacks. The secondary efficacy variables were: mean change from baseline in the proportion of patients with no angina attacks, systolic blood pressure, diastolic blood pressure, heart rate, and proportion of blood pressure responders. Number of patients reporting adverse effects (AEs) and severity of AEs in both of the groups were compared. All patients (n = 100) completed the study. In the S-metoprolol group the number of angina attacks (mean +/- SEM) at baseline and after 2, 4 and 8 weeks of therapy were 6.3 +/- 0.8, 3 +/-0.4, 1.8 +/- 0.4 and 0.7 +/- 0.2, respectively. In the metoprolol group these values were 5.8 +/-1, 3 +/- 0.7, 1.4 +/- 0.3 and 0.7 +/- 0.2, respectively. The reduction in the number of angina attacks from baseline was significant (p < 0.0001) in both groups with no between-group difference. The response rate in angina (percentage of patients completely relieved of angina attacks clinically) was greater in the S-metoprolol group (72%) when compared to the metoprolol group (62%) (p > 0.05, NS). Both study groups showed significant (p < 0.0001) reduction in baseline systolic blood pressure (SBP), diastolic blood pressure (SBP) and heart rate (HR) in hypertensive patients and a clinically non-significant (p > 0.05, NS) change in normotensive patients. Among hypertensive patients, the response rate in angina was higher in the S-metoprolol group (74%) when compared to the metoprolol group (61%) (p > 0.05, NS). In the S-metoprolol group four patients reported AEs: fatigue (n = 4), dry mouth (n = 1), dizziness (n = 1), dyspnea (n = 2), and mild rash (n = 1). In the metoprolol group three patients reported AEs: fatigue (n = 2), dyspnea (n = 1) and dizziness (n = 1). No statistically significant difference was detected between the groups in AE frequency/severity. In routine clinical practice in the management of angina (with or without coexisting hypertension), S-metoprolol administered at half the dose of the racemate, shows similar efficacy, safety and a trend towards a higher response rate.